The use of electrical batteries and affiliated battery chargers for appliances, machines and electrically powered toys is increasing significantly as battery efficiency and power output continues to be enhanced. Many of the batteries in use in such apparatus have significantly high ampere/hour capability with fully charged short circuit current capacity of up to 100 amperes. Even a run down 12 volt lead/acid type battery, having only 10 volts of output is capable of producing 30 amperes of short circuit current.
Recharging apparatus for such batteries typically includes the combination of a voltage reduction transformer and a rectifier, which plugs into a 110 volt a.c. outlet. Typically, an ordinary home appliance light duty electrical cord interconnects the battery recharger and the battery or battery set which is to be recharged. In some instances the batteries themselves are fused but the fuse ratings are set to accommodate typical operational current flows which most often exceed by a wide margin the normal level of approximately 1-2 amperes of recharging current. Accordingly, the battery fuse is of little use in protecting against current flows which may not disrupt the high current battery fuse but which would be in excess of that tolerable by the light duty electrical cord which interconnects the battery pack and the recharger device.
It is highly important that this recharger-battery circuit be protected from excessive currents since the electrical cord interconnecting the battery pack and the recharger is very susceptible to damage which may include a short circuit. It has been demonstrated that a short circuit in a four foot length of household electrical cord which is connected to a lead/acid 12 volt battery pack which has been run down to 10 volts can produce sufficient electrical current in the cord to cause it to become white hot in a short period of time. Obviously, an accidental circumstance of this kind where the battery recharging operation had been left unattended or where, if attended, the apparatus could not be mined off time, represents a serious fire hazard.
In order to block the electrical discharge of the battery or battery pack into the conductors which interconnect the recharging device and the battery it is mandatory to fuse the electrical cord itself. That can best be accomplished by providing a fusing system in the plug to which the conductors in the cord are connected.
Accordingly, it is the primary object of the present invention to provide an electrical conductor fusing system that will prevent a high current discharge of a battery into the conductors attached to the battery in the event that the conductors become shorted or interconnected with a low resistance connection.
Another object of the invention is to provide a fusing system for electrical cords where the fuse is carded by the electrical plug attached to one end of the conductors comprising the electrical cord.
A further object of the invention is to reduce the fire hazard potential of a damaged electrical cord.